eLetters

271 e-Letters

  • First study on effect and impact of mechanical ventilation in myotonic dystrophy type 1

    We thank Dr. Seijger and colleagues for their analysis. These queries are legitimate and most of the answers are in the online repository. Indeed, in order to comply with the guidelines for letters to Thorax (no more than 1000 words and 2 tables / figures), we could not include all our descriptive and univariate analysis.

    We agree that the analysis of survival of patients with type 1 myotonic dystrophy is complex. Our results in Figure 1 and Table R1 demonstrated that patients who refused to initiate NIV, or who delayed NIV initiation, had both a more severe respiratory function and a higher risk for severe event (invasive ventilation or death). Independently from determining whether these severe complications were due to the severity of the initial respiratory function, the lack of compliance to treatment or both, we believe that it was important to underline the presence of this triptych, which is not observed with other neuromuscular groups, such as Duchenne muscular dystrophy where the acceptance of NIV increases with the respiratory dysfunction severity.

    Our suggestion that failure to adhere to home mechanical ventilation was associated with increased mortality (tracheostomy excluded), was based on a Cox model analysing predictors of 10-year mortality among NIV users (Table 1). The Cox model was used to evaluate death risk ratios associated with NIV adherence category and was adjusted for other risk factors described in the literature. The covariates i...

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  • Reply to ‘effect and impact of mechanical ventilation in myotonic dystrophy type 1: a prospective cohort study.’

    To the editor,

    We read with great interest the paper of Boussaïd et al.1. They showed that Myotonic Dystrophy type 1 (DM1) patients who refused or delayed non-invasive ventilation were at higher risk for severe events, the latter defined as invasive ventilation or death. In the NIV users, risk of death was associated with orthopnoea and adherence to therapy. The investigators concluded that non-use or poor adherence of home mechanical ventilation (HMV) may be associated with increased mortality. Despite the importance of these findings several comments can be made.

    First, survival analyses in DM1 patients are complex due to heterogeneity and several other factors which have to be taken into account if the effects of HMV are assessed. For example not only the variance of reduced pulmonary function but also neuromuscular deficits, apathy, cardiac conduction disturbances, presence of obstructive or central sleep apnea do all influence the clinical condition and prognosis of these patients2. In addition, there remains the possibility that hypercapnia might not always be a result of ventilatory pump failure and that HMV might not be effective3. Correction for these confounders is needed to investigate the real effect of HMV. Moreover, both groups differ in vital capacity and presence of hypercapnia at baseline. So, we are not sure whether the risk of a severe event is really higher in the l/noNIV group than in the other groups. Therefore the presented difference...

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  • SHOULD I STAY OR SHOULD I GO? PULMONARY EMBOLISM AND AIR TRAVEL

    The global increase in air travel, with over 3.97 billion people traveling by air each year, and the ageing population, increase the number of those with an illness who wish to travel (1). Even more, in countries like Greece with hundreds of islands, health professionals are frequently asked to assess a patient’s fitness to fly. Doctors can receive advice and guidance mainly from two sources: the IATA passenger medical clearance guidelines (2) and the Aerospace Medical Association in which the British Thoracic Society’s recommendations for air travel (3) are suggested.
    Many respiratory conditions can affect a passenger’s fitness to fly with pulmonary embolism being the most debatable (3). A major question that respiratory physicians frequently have to answer, mostly with visitors from overseas who need to be repatriated following diagnosis of pulmonary embolism, is about the right time to “fly with a clot”. The British Thoracic Society guidelines recommend against airline travel during the first four weeks following pulmonary embolism (3). On the other hand, in the IATA medical guidelines published in 2018 it is suggested that patients can fly 5 days after an acute pulmonary embolism episode, if they receive anticoagulation and their PaO2 is normal on room air (2). Although there is little scientific evidence to support the above mentioned recommendations, the huge difference in the suggested period can really confuse healthcare professionals. Moreover, asking patie...

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  • Effect of inhaled corticosteroid dose on blood eosinophils

    Lommatzsch et al1 report significant falls in blood eosinophils in 11 asthma patients (mean FEV1 87%) in response to increasing the dose of inhaled corticosteroid from 1000ug to 2000ug/day (beclometasone equivalent dose ) ,with a median difference of 240 cells/ul . Jabbal et al 2 reported in 217 asthma patients (FEV1 85%) a mean fall of 71 cells/ul (95%CI 38-105) comparing 200ug verses 800ug belcometasone equivalent dose ,along with a 14.5ppb (95%CI 7.9-22.1) fall in FeNO. The patients reported by Lommatzsch et al had a higher baseline level of eosinophils with a median value of 560 cells/ul as compared to a mean value 356 cells/ul for Jabbal et al . Nonetheless we agree with the conclusion that the prevailing inhaled corticosteroid dose should be taken into consideration when making decisions to initiate treatment with biologics such as anti-IL5 and anti-IL4α, where the response is determined by levels of blood eosinophils .

    References

    1. Lommatzsch M, Klein M, Stoll P, Virchow JC. Impact of an increase in the inhaled corticosteroid dose on blood eosinophils in asthma. Thorax 2018. doi:10.1136/thoraxjnl-2018-212233
    2. Jabbal S, Lipworth BJ. Blood eosinophils: The forgotten man of inhaled steroid dose titration. Clin Exp Allergy 2018; 48:93-5.

  • Science is the great antidote to the poison of enthusiasm and superstition

    To the Editor

    Science is the great antidote to the poison of enthusiasm and superstition

    We thank Langer and colleagues for their interest in our editorial. In many ways the title they have chosen for their response confirms our thesis. ‘Absence of evidence’ may not be ‘Evidence of absence’ but it is ……………….. Absence of evidence . Our contention overall is that the relentless search for benefit despite the recently reported negative trials is driven by emotion rather than data.
    Whilst physiological arguments are of interest to physiologists, there remains no convincing evidence in our view either that respiratory muscle fatigue is present in patients with COPD, or that it contributes to exercise limitation. The various suggestions they make in the hope of eliciting a ‘positive result’ for IMT (e.g. changing outcome measure, patient selection) are credible research suggestions and we would not oppose interested investigators pursuing research in this arena, but this does not alter our contention that IMT has no place in current clinical practice.
    Clinically their argument is that IMT alone is beneficial in COPD. We think this argument is specious (irrespective of whether it is correct); pulmonary rehabilitation, in part thanks to the Leuven group, has one of the strongest evidence bases for any therapy in COPD. Therefore the idea that one might drop PR in order to do IMT instead is not one we believe should be taken into the clinical arena....

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  • The importance of experimental conditions in the assessment of products relevant to human consumption

    Although electronic cigarettes (ECs) are a much less harmful alternative to tobacco cigarettes, there is concern as to whether long-term ECs use may cause risks to human health. There are reasonable concerns and should be elucidated as soon as possible to learn how to best employ these products, causing the least possible damage to users.
    Scott and colleagues aimed at define whether e-cig vapors have a negative impact on human alveolar macrophages (AMs) viability and function (1). They tested human AMs from lung resection specimens from healthy donors by exposing these cells to the electronic cigarette vapour condensate (ECVC).
    First of all, the authors dedicated a detailed explanation to the method used to condensate the vapour, but the protocol used to generate vapour is quite ambiguous, omitting to indicate puff volume, puff number, and in particular if the pump used to aspirate the vapors were able to generate the correct puff profile (2). This is a crucial step in the validation process of an exposure method, because if the vapours are generated with incorrect regimes, they can lead to the production of inaccurate ECVC and thus to distorted results invalidating all the conclusions of the study. We think the author could detail the regimen employed for vapour generation.
    Furthermore, airway macrophages are resident in the connective tissue and not exposed directly to the liquid-air interface, therefore the method used for the exposition of these cells...

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  • Additional differentitation

    The differentiation between an empyema and a peripheral lung abscess is really difficult. The authors have summarized most points on differentiation. We had of a similar case, which looked like an Abscess on Chest Xray and had Acute angulation with lungs on Chest Ct, but due to the smooth inner walls and enhancement of pleura, we treated the case like an Empyema. Interestingly the initial CT showed some volume loss with ribs appearing crowded and this feature was more pronounced in the subsequent CT done after 2 weeks. Thus, associated volume loss with rib crowding could also be an additional point in the differentiation favoring Empyema and this volume loss might appear fairly early as well.

    ****can provide CT films of the same****

  • Cost-effectiveness and tuberculosis elimination: never the twain shall meet

    The National Institute for Health and Care Excellence (NICE) 2016 Tuberculosis (TB) guidelines no longer recommend screening contacts of adults with extra-pulmonary TB (ETB). However, no new evidence since the previous published guidelines was provided to support this policy change. Moreover, despite the guidance, some regional TB multidisciplinary teams and services continue to screen ETB contacts.(1)

    In their original article in Thorax, Cavany et al estimated the cost-effectiveness of screening ETB contacts in London.(2) The authors’ findings suggest that screening of such contacts is unlikely to be cost-effective at the threshold of £30,000/QALY - the “willingness to pay” threshold commonly used by NICE.(3) The authors’ findings are tempered by the data being London-specific and not generalizable to the rest of England, and the lack of robust available evidence on either transmission rates or index cases’ pre-diagnosis symptom duration. Nevertheless, the authors recognise these limitations and their sensitivity analysis suggests that, even with assumptions of higher rates of transmission or prolonged symptom duration, their principal findings would not change.

    The findings of this strong, well-designed study are important and provide much needed evidence for national debate around strategies for TB contact screening. Resources for TB services across England, especially those allocated to tracing contacts of TB patients, are becoming increasingly constrain...

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  • Impact of electronic cigarette on our health

    According to recent study published by Sebastian et al., (1) electronic cigarette vapor impairs the activity of alveolar macrophages, which engulf and remove dust particles, bacteria, and allergens that have evaded the other mechanical defenses of the respiratory tract. This study finding is important and it shows that the long term health impact of e-cigarettes use may be more harmful than we know (2).

    Meanwhile, industry, tobacco research community and the online information are promoting electronic cigarette as a less harmful tobacco cessation tool. However, before more leeway to advertise the harm-reduction benefits of vaping products, we believe that the first step would be to establish whether vaping products are indeed safer tobacco cessation device or harm reduction tool (3). Moreover, currently available evidence (including clinical guidelines and position statements of credible medical organizations) based information need to ensure that people are protected from commercial interests and are able to make informed decisions based on current best evidence on electronic cigarette and its long term health effects (3). It is our moral obligation that we should not be promoted electronic cigarette to our children and people those who never wanted to smoke tobacco. At the same time, it is important to promote the proven non-tobacco nicotine products such as Nicotine Replacement Therapy (gum or inhalators) to smokers those who are sincerely wanted to quit.

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  • Absence of evidence is not evidence of absence! Lessons from recent trials of adjunctive IMT in COPD and recommendations for further research: careful selection of candidates, controlling interventions and choosing the most adequate outcomes.

    We support the view of Drs. Polkey and Ambrosino that recommendations for clinical practice should not be based on either positive or negative preoccupation concerning the potential effectiveness of a treatment but rather on an impartial evaluation of the available data. In their editorial entitled ‘Inspiratory Muscle Training in COPD: can data finally beat emotion’ they unfortunately provide a fairly one-sided evaluation of this treatment, based on an incomplete and largely outdated review of the available evidence1. It is unfortunate that they neglect a major part of available data, which could contribute to a more balanced and fair discussion about this intervention. We therefore deemed it necessary to add this missing evidence along with our own interpretation of recent findings to the discussion.
    Complexity of studying add-on interventions to pulmonary rehabilitation
    Based on the results from three recent multicentre trials2-4, Polkey and Ambrosino exclude a role for adjunctive IMT in the rehabilitation of patients with COPD. As emphasized in a previous opinion piece by Dr. Ambrosino5, it is important to distinguish between studies that evaluate the effects of inspiratory muscle training (IMT) as a standalone intervention (i.e. in comparison to no intervention or a sham control intervention) and studies on the effects of IMT added to a pulmonary rehabilitation program (PRP).
    Concerning the first comparison, there is a large amount of data available s...

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